Flexible lead connection



July 18, 1939. w. T. ALLEN ET AL FLEXIBLE LEAD CONNECTION Filed April 5, 1937 w j a .7 E 1 l w 9 w w 1 M w Z d i l y z a U f 0 w w a 9 M 9 p (L a 2 a Z4 7 z 2 WM 4 5. a M M 1 I l// /////MIIE Patented July 18, 1939 UNITED STATES PATENT OFFICE FLEXIBLE LEAD CONNECTION gan Application April 5, 1937, Serial No. 135,013

7 Claims. (01. 219-12) This invention relates to electrical instrumentalities and more particularly to flexible lead connections for electrically connecting relatively movable parts therein.

One object of the present invention is the provision of an improved flexible lead connection and the method of attaching the same which results in a very firm joint which may be quickly and economically made while avoiding the possibility of stiffening of the flexible conductor due to the rimning of the soldering material.

Another object of the invention is the provision of a flexible lead connection which results in a relatively firm joint between the end of the flexible conductor and the solid part while maintaining a thin wrapping about the conductor strands remote from the part to provide a binding or retaining means for them.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specification and appended drawing illustrating certain preferred embodiments of the invention in which:

Figure 1 is a vertical sectional view of an automatic electric circuit breaker employing a flexible lead according to the present invention.

Figure 2 is a broken oif view similar to Figure 1 showing the parts in a. diflerent circuit relation.

Figure 3 is a view illustrating one means of providing the individual leads to be applied.

Figure 4 is a viewshowing an individual lead before attachment.

Figure 5 is a sectional view on the line V-V of Figure 4.

The joint and method of the present invention have been illustrated in connection with the circuit breaker disclosed and claimed in the copending applications of John G. Jackson, Serial No. 36,247 flied August 15, 1935; (now Patent No. 2,132,625, grantedOctober 11, 1938), Serial No. 72,035 filed April 1, 1936 (now Patent No. 2,096,545, granted October 19,1937); Serial No. 77,519 flied May 2, 1936 (now Patent No. 2,132,627, granted October 11, 1938); all entitled Circuit'breakers, and in the divisions and continuations of these applications. It is, of course, to be understood that the connection means and .method is of general application and may be ap-.

plied in any sort of electrical instrumentality where electrical connection is desired between relatively moving parts. The circuit breaker illustrated in Figures 1 and 2 comprises a metallic backing portion l which may'comprise the back wall of an outer enclosing box upon which is mounted an insulating base 2 having a metallic cover 3 and an insulating cover liner and end shield 4. Generally centrally of the base is mounted a stationary contact plate 5 as by means of a stud 6 and carrying stationary contact surfaces thereon adapted to cooperate with movable contact surfaces 1 upon the ends of floating conducting contact bars 8. Rectilinearly movable U-shaped members 9 are provided guided by formations on the base for movement at right angles to the back of the base and these members have their longer legs provided with slots ll receiving notches l2 in the upper edges of the bars 3. Compression springs l3 are provided intermediate thebars and the bottom of the base. Rotary handles ll projecting through the cover 3 are provided mounted on shafts i5 and having interior camming surfaces including stable flat "oiP portions l6 and resetting tips ll. Light handle position retaining springs l8 are provided to bias the handles into engagement with the members 9.

Upon end latches at the exterior of the breaker enclosure connectors l9 are rigidly secured as by spun over portions of metallic inserts 2| which also receive terminal connectors 22. Upon the innerends of the connectors l9 are mounted bimetallic members 23, this mounting including adjustment means indicated generally at 24.- The free ends of the bimetallic members 23 serve to latch the ends of the contact bars 8 remote from the contact surfaces 1 and these free ends are connected with intermediate points on the bars 8 by means of flexible leads 25 connected to the bimetals and the bars in a manner to be hereinafter described. The chamber adjacent the cooperating contacts is provided with an insulating' liner 26 and with barriers 21 having slots adjacent their bottom portions closely receiving the contact bars 8. 4

The circuit'breaker mechanism shown at the top of Figure '1 is in the closed circuit or normal operating position with the circuit closed from the stationary contact plate 5 through the bar 8, flexible lead 25, bimetal 23 to the exterior of the breaker enclosure. Current may be led to the contact plate 5 through what may be termed a main circuit breaker mechanism or through a solid connector, not shown. To move the mechanism shown at the top of Figure 1. to the off position the handle is rotated in a counterclockwise direction by which the parts assume the position shown in reverse at the bottom of Figure 1 and in this position the flat surface I6 on the handle engages the flat surface at the top of the member 9 and results in a stable manbar 8 whereupon the bar has rotated under the action of the compression spring 83 about its engagement with the member it into the position shown. In this movement the heavy compression spring I3 serves to compress the light handle biasing spring l8 and moves the handle into a position indicating the overload tripposition of the circuit breaker. To reset the parts after an automatic trip the operating handle is moved as far as possible past the foff position. As this movement proceeds the member Q will be moved downwardly engaging the contact carrying end of the bar 8 with the bottom of the arc chamber and thereupon rotating the latching end of the bar downwardly. In its final movement when the resetting tip 81 is engaged with the top surface of the member 9 the latching end of the contact bar will be beyond the free end of the bimetal and assuming that the bimetal has in the meantime cooled sufliciently to return to its latching position, will replace the parts in manual off position whereupon movement of the handle to the on position will permit the bar 8 tomove upwardly under the bias of spring 03 into engagement with its cooperating stationary contact.

In Figure 3 there is shown a continuous flexible conductor 3! about which at predetermined spaced intervals are wrapped thin strips of solder material 32. These strips are thereafter cut at a medial point as indicated at 33 which results in the formation of the individual flexible lead or conductor 34 shown in Figure 4 having strips of solder material wrapped around both its ends. It is to be noted that this method of placing the solder strip about the ends results in the formation of two wrapped ends by each wrapping and cutting operation. It is, of course, obvious that these ends may be individually applied if desired or that the double strip wrapping and cutting may be done singly at a spaced distance from the last cut end of the conductor 35.

Figure 5 illustrates a section through a wrapped end in Figure 4 and shows the interior finely stranded cable or lead 34 having a metal wrapping 32 therearound. In applying this flexible lead 34 to solid parts which, in the specific instance illustrated, are constituted by the free end of the bimetallic member 23 and an intermediate point on the contact bar t the wrapped end of the lead may be placed against the part at the point of attachment and the part and lead end pressed together between electrodes where upon the passage of current through the electrodes is adjusted to fuse substantially only the portion of the wrapping placed against the fixed part leaving the outer portion intact as a wrapping about the ends of the cable strands. This fusing or brazing operation may be done with facility upon a spot welding machine.

Applicants invention has so far been disclosed in its specific aspects. However, in its broader terms it includes the brazing of a flexible conductor end to a solid part by means of a piece of solid soldering material placed between the end of the lead and the solid part and fused by any desired method but for which the opergreases ation similar to spot welding is particularly adapted. This portion of solid solder is carefully limited in volume so that while there is produced molten solder which will flow into the strands of the cable, insuflicient solder is used to permit the flowing of the solder up the strands of the conductor by capillary action such as occurs by the use of liquid soldering and which results in rendering the flexible lead stiff and more apt to break in the operation of the parts.

While applicants invention in its broader aspect is to be construed as including the attaching of a flexible lead by the placing of a selected quantity of solid soldering material be tween the end of the lead and the solid part to which it is to be attached and the fusing of this portion of solder to form the bond, which selected quantity is suflicient to permit flow into the strands of the lead but insuflicient to allow flow up the strands by capillary action, still the wrapping method previously described is preferred as it provides not only for the fusing of this small quantity of solder to avoid the capillary action referred to but also results in the maintaining of the wrapped strip about the portion of the lead away from the part to which it is attached whichwrapping then functions as a binding to prevent strands of the cable from loosening from the joint. Applicants invention not only avoids the necessity of any mechanically attached end, more particularly the. use of a separate encasing terminal lug to which the flexible lead might otherwise have been soldered, but also avoids the flow of solder up the strands by capillary action which is hardly to be avoided in the use of a liquid solder. J The construction lends itself to rapid and economical production with the attainment of a strong joint and a fully flexible lead.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. The method of attaching the end of a stranded, flexible conductor to a solid part in electrically conducting relation which comprises wrapping said conductor end with a thin strip of solid solder, applying said wrapped end to the solid part to which it is to be attached, fusing the portion of said wrapping lying against the part to firmly braze the conductor end to the part, and maintaining the portion of the wrapping away from the part in a solid state to provide a binding for the conductor strands.

2. The method of attaching the end of a stranded, flexible conductor to a solid part in electrically conducting relation which comprises wrapping said conductor end with a thin strip of solid solder, applying said wrapped end to the solid part to which it is to be attached, fusing the portion, of said wrapping lying against the part to'firrnly braze the conductor end to the part, and maintaining the portion of the Wrapping away from the part in a solid state to provide a binding for the conductor strands, the quantity of solder actually fused being insuflicient to provide for flow along the conductor strands away from the point of attachment, whereby stiffening of the conductor isavoided.

3. The method of attaching the end of a stranded, flexible conductor to a solid part in electrically conducting relation which comprises wrapping said conductor and with a thin strip of solid solder, applying said wrapped end to the solid part to which it is to be attached, fusing the portion of said wrapping lying against the part to firmly braze the conductor end to the part, and maintaining the portion of the wrapping away from the part in a solid state to provide a binding for the conducting strands, the

portion of said wrapping actually fused being sufllcient to provide for solder flow into the strands at the point of attachment but insufllcient to permit solder flow along the strands away from the point of attachment.

4. A unit assembly attachment between a flexible, stranded conductor and a solid part including a thin strip wrapping of solder about the end of the conductor with the portion of said wrapping immediately adjacent the part fused thereagainst and firmly brazing the conductor to the part and with the portion of said wrapping remote from the part substantially intact and providing a binding for the conductor strands.

5. A unit assembly attachment between a flexible, stranded conductor and a solid part comprising a thin strip wrapping of solder about the end of the conductor with the portion of said wrapping immediately adjacent the part fused thereagainst and flrmly brazing the conductor to the part and with the portion of said wrapping remote from the part substantially intact and providing a binding for the conductor strands, said fused portion being distributed in the conductor strands only immediately adjacent to the point of attachment.

' 6. The method of attaching the enii of a stranded, flexible conductor, composed of individual strands twisted together and of a flnenes making the conductor susceptible to a substantial diffusion of molten metal along the strands by capillary action from the point of application, to a substantially flat surface on' a solid part in electrically conducting relation without the use of a terminal or lug which comprises selecting a portion of solid solder of a quantity to provide for flow of melted solder into the conductor strands at the point of attachment while substantially inhibiting the diffusion or flow of molten solder along the conductor strands by this capillary action, placing this solid solder between said flat surface and said conductor end, and electrically brazing said end to said part through said solder by passing current therethrough between electrodes pressed thereagainst.

7. The method of attaching the end of a stranded, flexible conductor,-having individual strands of a fineness making the conductor susceptible to a substantial diffusion of molten metal along the strands by capillary action from the point of application, to a substantially flat 7 surface of a solid part in electrically conducting relation without the use of a terminal or lug which comprises placing a'portion of solid solder between said conductor end and'said flat surface. pressing said conductor end, solder portion and flat surface together between electrodes, and passing current between said electrodes to fuse at least a part of said solder portion, said at least a part of said solder portion being so small in volume as to inhibit' the diifusion or flow of solder up the conductor strands by capillary action, thus preventing stiffening of the conductor adjacent to the joint, while providing for flow of solder into the conductor strands at the joint, thus binding them together and to said solid Part.

WALLACE T. ALLEN.

OLAV MASENG. 

